Intellectual custom is a second nature. What we are accustomed to seems obvious to us. As Sean Collins has recently reminded us many things which the intellectual culture of our day takes as self-evident are in fact highly questionable positions introduced by the Enlightenment. One area in which this is particularly hard to spot is in our concept of number. Nothing seems so obvious and immediate to us as our idea of number, and yet the ancients had a very different idea of what numbers are than we. Jacob Klein’s Greek Mathematical Thought and the Origin of Algebra tries to get to the root of that difference, and by so doing he gets to the roots of the transformation that gave us modern science and philosophy. Leo Strauss explains:
Nothing affected [Klein and me] as profoundly in the years in which our minds took their lasting directions as the thought of Heidegger. This is not the place for speaking of that thought and its effects in general. Only this much must be said: Heidegger, who surpasses in speculative intelligence all his contemporaries and is at the same time intellectually the counterpart to what Hitler was politically, attempts to go a way not trodden by anyone or rather to think in a way in which philosophers at any rate have never thought before. Certain it is that one has questioned the premise of philosophy as radically as Heidegger. While everyone else in the young generation who had ears to hear was either completely overwhelmed by Heidegger, or else, having been almost completely overwhelmed by him, engaged un well-intentioned but ineffective rearguard actions against him, Klein alone saw why Heidegger is truly important: by uprooting and not simply rejecting the tradition of philosophy, he made it possible for the first time after many centuries—one hesitates to say how many—to see the roots of the tradition as they are and thus perhaps to know, what so many merely believe, that those roots are the only natural and healthy roots. Superficially or sociologically speaking, Heidegger was the first great German philosopher who was a Catholic by origin and by training; he thus had from the outset a premodern familiarity with Aristotle; he thus was protected against the danger of trying to modernize Aristotle. But as a philosopher Heidegger was not a Christian: he thus was not tempted to understand Aristotle the light of Thomas Aquinas. Above all, his intention was to uproot Aristotle: he thus was compelled to disinter the roots, to bring them to light, to look at them with wonder. Klein was the first to understand the possibility which Heidegger had opened without intending it: the possibility of a genuine return to classical philosophy, to the philosophy of Aristotle and Plato, a return with open eyes and in full clarity about the infinite difficulties which it entails. He turned to the study of classical philosophy with a devotion and a love of toil, a penetration and an intelligence, an intellectual probity and a sobriety in which no contemporary equals him. Out of that study grew his work which bears the title “Greek Logistics and the Genesis of Algebra.” No title could be less expressive of a man’s individuality and even of a man’s intentions; and yet if one knows Klein, the title expresses perfectly his individuality, his idiosyncrasy mentioned before. The work is much more than a historical study. But even if we take it as a purely historical work, there is not, in my opinion, a contemporary work in the history of philosophy or science or in “the history of ideas” generally speaking which in intrinsic worth comes within hailing distance of it. (Leo Strauss, “An Unspoken Prologue”)
It is interesting that Strauss sees Heidegger as having enabled Klein to go back to them without reading them through the lens of modern philosophy. In a brilliant letter to Mortimer Adler Charles De Koninck discusses the uselessness of trying to argue with modern philosophers. They have concealed the principles of their thought from themselves. They consider univocism, voluntarism, and nominalism, as simply given for reason; they do not consider that their view is in fact the result of a decision to pursue power instead of truth. Thus the true philosopher can never come to any real meeting of minds with his adversary. In an epilogue to a recent paper I argue that the very radicalism of certain contemporary philosophers allows for a possibility of a discussion which De Koninck did not anticipate. The philosophers I had in mind are certain contemporary “post-post-modern” theorists, but obviously they are all more or less influenced by the “intellectual counterpart of Hitler” who was of such decisive assistance to Klein.